A school district in Michigan has canceled classes for three days after students received messages threatening school violence in the aftermath of a teacher’s arrest on sex charges. Atherton Community Schools announced the closures effective Wednesday through Friday after students were sent the threats via AirDrop—an Apple file-sharing platform—on Tuesday morning. Superintendent John Ploof wrote to parents saying it was clear to him the threats had been made by students in the school building. “As a district, we take the safety of our students and staff very seriously,” Ploof wrote. “The stress resulting from these threats along with the recent arraignment of one of our teachers has reached levels that have us extremely concerned.” Last Friday, music teacher Jerry Cutting, 54, was arrested and charged with several counts of first-degree criminal sexual conduct for having alleged sexual relations with a 14-year-old student.